Photon emitters that produce near field illumination are sometimes used in, e.g., magnetic recording heads, in which the photon emitter is used to heat the recording medium. For example, near field photon emitters are used in heat assisted magnetic recording (HAMR). Other applications of near field photon emitters include, e.g., optical fibers, plasmon tips for optical near field microscopy (SNOM), nano-photonics devices, optical wave-guides, and laser-diodes. Characterization of such near field photon emitters, such as the size of the aperture or power, is useful. Additionally, characterization of far field photon emitters, such as the beam waist of a focused laser may be useful. Accordingly, an improved metrology method for characterizing photon emitters is desired.